This application is related to the field of wireless networking devices, and in particular to systems and methods for controlling network traffic to and from clients. Networking devices enable data communications between two or more devices, referred to generally as clients. Data communications may be conducted over wired and/or wireless network interfaces. Typically, data is partitioned into packets, which are then communicated via one or more networking devices to one or more destination clients.
Networking devices may handle packets generated by and directed to large numbers of clients over the same interface. The bandwidth or data communications capacity of networking devices limits the amount of data or the rate of network packets passing through network devices. The limits on bandwidth are particularly acute in network devices including wireless network interfaces. If the bandwidth limit of a networking device is reached or exceeded by its client's network traffic, packets may be delayed or dropped. Depending on the type of data being communicated over the network, these traffic disruptions caused by reaching or exceeding bandwidth limit of a networking device may adversely affect the performance of applications on a client. For example, clients receiving voice or streaming video data may be adversely affected by even small delays or losses of packets.
Because of the limits on network device bandwidth, many network devices include quality of service (QoS) functionality. Quality of service functionality allows network administrators to provide different priority for packets or other network data based on factors such as the associated client, user, client application, or data flow. Typically, users, clients, or applications are assigned to different quality of service profiles. Each quality of service profile specifies a quality of service parameters to associated packets or other network data. Networking devices use the scheduling weights to prioritize packet traffic and potentially guarantee a minimum level of performance to some or all of the network data flows.
However, typical quality of service functionality does not take into consideration performance issues unique to wireless network interfaces. For example, many wireless network interfaces support multiple wireless networking standards, such as IEEE 802.11a, 802.11b, 802.11g, and 802.11n. This allows the networking device to support legacy clients using slower (e.g. relatively low data-rate) standards, such as 802.11b, as well as newer clients capable of communicating via faster (e.g. relatively high data-rate) standards, such as 802.11n. When a networking device is operating in a mixed mode and communicating with clients via multiple standards, the clients using slower data rates, such as clients using older standards or newer standards at lower data rates, for example due to lower signal strength or radio interference, will consume a disproportionate amount of airtime from the wireless network interface. As a result of this disproportionate airtime usage, the performance of other clients attempting to utilize faster data rates will be degraded substantially.